How long do the diffusers last?

On average, our diffusers last between 250-300 puffs. This is based on using them as directed; short puffs from the diffuser, and between 3-9 total puffs per day. At around 3 puffs at a time, and no more than 3 times a day, the average diffuser lasts between 3 and 4 weeks.